| Md. Wasim Aktar | | | | susceptibilities ofmarine fishes exposed to |
| | | | herbicide. Bull. Environ. Contam. Toxicol. |
| Pesticide Residue Laboratory, Department of | | | | 56:655-662. |
| Agricultural Chemicals, Bidhan Chandra | | | | |
| Krishi Viswavidyalaya, Mohanpur-741252, | | | | 5. Extoxnet. 1996. Pesticide Information |
| Nadia, West Bengal, India | | | | Profile: oryzalin. June. |
| | | | |
| Introduction Pesticides are found as common | | | | 6. Shafiei, T.M., and H.H. Costa. 1990. The |
| contaminants in soil, air, and water, and on | | | | susceptibility andresistance of fry and |
| non-target vegetation in our urban | | | | fingerlings of Oreochromis mossambicus Peters |
| landscapes. Once there, they can harm plants | | | | to some pesticides commonly used in Sri |
| and animals ranging from beneficial soil | | | | Lanka. Journal Appl. Ichthyol . 6:73-80. |
| microorganisms and insects, non-target | | | | |
| plants, fish, birds, and other wildlife. | | | | 7. Folmar, L.C., H.O. Sanders, and A.M. |
| Table 1 summarizes the harmful effects to | | | | Julin. 1979. Toxicity of the herbicide |
| non-target organisms of some commonly used | | | | glyphosate and several of its formulations to |
| urban herbicides. | | | | fish and aquatic invertebrates. Arch. |
| | | | Environ. Contam. Toxicol. 8:269-278. |
| Table 1 . Harmful effects of selected | | | | |
| herbicides on non-target organisms | | | | 8. Morgan, J.D. et al. 1991. Acute avoidance |
| Source: Sanders, 1969 | | | | reactions and behavioral responses of |
| | | | juvenile rainbow trout ( Oncorhynchus mykiss) |
| Fish When pesticides contaminate water they | | | | to Garlon 4, Garlon 3A, and Vision |
| can be harmful to the fish that live there. | | | | herbicides. Environ Toxicol. Chem. 10:73-79. |
| Insecticides can be particularly toxic to | | | | |
| fish. Chlorpyrifos, a common contaminant of | | | | 9. Liong, P.C., W.P. Hamzah, and V. Murugan. |
| urban streams,18 is very highly toxic to | | | | 1988. Toxicity of some pesticides towards |
| fish, and has caused fishkills in waterways | | | | freshwater fishes. Malaysian Agric. J. |
| near treated fields or buildings.1,2 | | | | 54(3):147-156. |
| Diazinon, also commonly found in urban | | | | |
| streams,18 is acutely toxic to many species | | | | 10. McBride, J.R., H.M. Dye, and E.M. |
| of fish, including salmon.3 Herbicides can | | | | Donaldson. 1981. Stress response of juvenile |
| also be toxic to fish. According to the EPA, | | | | sockeye salmon ( Oncorhynnchus nerka) to the |
| studies show that trifluralin, an active | | | | butoxyethanol ester of |
| ingredient in the weed-killer Snapshot, "is | | | | 2,4-dichlorophenoxyacetic acid. Bull. |
| highly to very highly toxic to both cold and | | | | Environ. Contam. Toxicol. 27:877-884. |
| warmwater fish."4 It was also shown in a | | | | |
| series of different tests to cause vertebral | | | | 11. Little, E.E. 1990. Behavioral indicators |
| deformities in fish.5 Oryzalin, the active | | | | of sublethal toxicity of rainbow trout. Arch. |
| ingredient of Surflan, also is 'highly toxic' | | | | Environ. Contam. Toxicol. 19:380-385. |
| to fish.6 The weed-killers Ronstar and | | | | |
| Roundup are also acutely toxic to fish.7,8 | | | | 12. Zaffaroni, N.P. et al. 1986. The toxicity |
| The toxicity of Roundup is likely due to the | | | | of 2,4- dichlorphenoxyacetic acid to the |
| high toxicity of one of the inert ingredients | | | | adult crested newt. Environ. Res. 41:79-87. |
| of the product. In addition to direct acute | | | | |
| toxicity, some herbicides may produce | | | | 12. Suwalsky, M. et al. 1999. Toxic action of |
| sublethal effects on fish that lessen their | | | | the herbicide 2,4-D on the neuroepithelial |
| chances for survival and threaten the | | | | synapse and on the nonstimulated skin of the |
| population as a whole. Glyphosate or | | | | frog Caudiverbera caudiverbera. Bull. |
| glyphosate-containing products can cause | | | | Environ. Contam. Toxicol. 62:570-577. |
| sublethal effects such as erratic swimming | | | | |
| and labored breathing which increase the | | | | 14. Caldwell, R.S. et al. 1979. Toxicity of |
| fish's chance of being eaten.9,10 2,4-D | | | | the herbicides 2,4-D, DEF, propanil and |
| herbicides caused physiological stress | | | | trifluralin to the Dungess crab Cancer |
| responses in sockeye salmon,11 and reduced | | | | magister. Arch. Environ. Contam. Toxicol. |
| the food gathering abilities of rainbow | | | | 8:383-396. |
| trout.12 | | | | |
| | | | 15. Cheney, M.A., R. Fiorillo, and R.S. |
| Other Aquatic Animals and Plants In addition | | | | Criddle. 1997. Herbicide and estrogen effects |
| to fish, other marine or freshwater animals | | | | on the metabolic activity of Elliptio |
| are endangered by pesticide contamination. | | | | complanata measured by calorespirometry. |
| 2,4- D or 2,4-D containing products have been | | | | Comp. Biochem. Physiol. 118C:159-164. |
| shown to be harmful to newts,13 frogs,14 | | | | |
| crabs,15 shellfish,16 and other aquatic | | | | 16. U.S. EPA. Office of Pesticide and Toxic |
| species.17,18 The weed-killer trifluralin is | | | | Substances. Office of Pesticide |
| moderately to highly toxic to aquatic | | | | Programs.1989. Pesticide factsheet: |
| invertebrates, and highly toxic to estuarine | | | | 2,4-dichlorophenoxyacetic acid. Washington |
| and marine organisms like shrimp and mussels. | | | | D.C., Sept. |
| Diuron is also highly toxic to aquatic | | | | |
| invertebrates.19 Since herbicides are | | | | 17. Sanders, H.O. 1969. Toxicity of |
| designed to kill plants, it makes sense that | | | | pesticides to the crustacean Gammarus |
| herbicide contamination of water could have | | | | lacustris. Technical Papers of the Bureau of |
| devastating effects on aquatic plants. In one | | | | Sport Fisheries and Wildlife No. 25. US Dept. |
| study, oxadiazon was found to severely reduce | | | | of Interior Fish and Wildlife Service, |
| algae growth.20 Algae is a staple organism in | | | | Washington D.C. (Jan.) |
| the food chain of aquatic ecosystems. Studies | | | | |
| looking at the impacts of the herbicides | | | | 18. Extoxnet. 1996. Pesticide Information |
| atrazine and alachlor on algae and diatoms in | | | | Profile: diuron. June. |
| streams showed that even at fairly low | | | | |
| levels, the chemicals damaged cells, blocked | | | | 19. Ambrosi, D., A. Isensee, and J. Macchia. |
| photosynthesis, and stunted growth in varying | | | | 1978. Distribution of oxadiazon and phoslone |
| ways.20 Another important class of organisms | | | | in an aquatic model ecosystem. American |
| is the cyanobacteria. Cyanobacteria live in | | | | Chemical Society 26(1):50-53. |
| aquatic environments as well as soil, and | | | | |
| play a crucial role in nitrogen fixation, | | | | 20. U.S. Water News Online. 2000. Ecologist |
| helping plants convert atmospheric nitrogen | | | | says effect of herbicides on aquatic |
| into nitrate compounds that the plant can | | | | environment needs research. July. |
| use. Trifluralin was found to inhibit the | | | | tecosay7.html. |
| growth of two common cyanobacteria at all | | | | |
| levels of application.21 | | | | 21. Kobbia, I. A., et al. 1991. Growth |
| | | | criteria of two common cyanobacteria isolated |
| Insects and Spiders In addition to killing | | | | from Egyptian flooded soil, as influenced by |
| insect "pests," insecticides obviously have | | | | some pesticides. Water, Air, and Soil |
| the potential to harm non-target insects such | | | | Pollution 60:107-116. |
| as beneficial natural predators and | | | | |
| pollinators. Less obviously, weed-killers can | | | | 22. Hassan, S.A. et al. 1988. Results of the |
| also be harmful to beneficial insects. One | | | | fourth joint pesticidetesting programme |
| study found that exposure to freshly dried | | | | carried out by the IOBC/WPRS-Working Group |
| Roundup (glyphosate) killed over 50 percent | | | | "Pesticides and Beneficial Organisms." J. |
| of three species of beneficial insects: a | | | | Appl. Ent. 105:321-329. |
| parasitoid wasp, a lacewing and a ladybug. | | | | |
| Over 80 percent of a fourth species, a | | | | 23. Extoxnet. 1996. Pesticide Information |
| predatory beetle was killed."22 Moderate | | | | Profile: 2,4-D. June. |
| doses of the herbicide 2,4-D severely | | | | |
| impaired honeybee brood production. 23 The | | | | 24. Washington State Department of |
| herbicide oxadiazon is also toxic to bees, | | | | Transportation. 1993. Draft roadside |
| which are pollinators.24 Herbicides may hurt | | | | vegetation management environmental impact |
| insects or spiders indirectly as well, such | | | | statement, appendix B, B2-10. |
| as when they destroy the foliage that these | | | | |
| animals need for food and shelter. For | | | | 25. Asteraki, E.J., C.B. Hanks, and R.O. |
| example, spider and carabid beetle | | | | Clements. 1992. The impact of the chemical |
| populations declined when 2,4-D applications | | | | removal of the hedge-based flora on the |
| destroyed their natural habitat.25 Birds | | | | community structure of carabid beetles (Col. |
| The insecticide diazinon is notorious for | | | | Carabidae) and spiders (Araneae) of the field |
| causing bird kills. Over 50 incidents | | | | and hedge bottom. J. Appl. Ent. 113:398-406. |
| involving the deaths of up to 1000 birds have | | | | |
| been documented in every region of the U.S.95 | | | | 26. US EPA. 1988. Diazinon; Ciba-Geigy |
| Diazinon is so lethal to birds that the EPA | | | | Corporation, et al., petitioners. Federal |
| estimates that between 15 and 80 minutes of | | | | Register 53(65):11119-11131. (April 5). 27. |
| grazing on diazinon treated turf is enough to | | | | US EPA. 1998. R.E.D. facts rodenticide |
| kill a bird.26 Non-target birds may also be | | | | cluster. Office of Prevention, Pesticides, |
| killed if they ingest poisoned grains set out | | | | and Toxic Substances (July). |
| as bait for pigeons and rodents.27, 28 | | | | |
| Avitrol, a commonly used pigeon bait, poses a | | | | 28. Extoxnet. 1996. Pesticide Information |
| large potential for ingestion by non target | | | | Profile: 4- Aminopyridine. June. pips |
| grain feeding birds. It can be lethal to | | | | 4-aminop.htm. |
| small seed-eating birds.29 rodifacoum, a | | | | |
| common rodenticide, is highly toxic to birds. | | | | 29. Duffard, R., L. Traini, and A. |
| It also poses a secondary poisoning hazard to | | | | Evangelista de Duffard. 1981. Embryotoxic and |
| birds that may feed on poisoned rodents.30 | | | | teratogenic effects of phenoxy herbicides. |
| Herbicides can also be toxic to birds. | | | | Acta Physiol. Latinoam. 31:39-42. 30. Lutz, |
| lthough trifluralin was considered | | | | H. and Y. Lutz-Ostertag. 1972. The action of |
| "practically nontoxic to birds" in studies of | | | | different pesticides on the development of |
| acute toxicity, birds exposed multiple times | | | | bird embryos. Adv. Exp. Med. Biol. |
| to the herbicide experienced diminished | | | | 27:127-150. |
| reproductive success in the form of cracked | | | | |
| eggs. Exposure of eggs to 2,4-D reduced | | | | 31. MacKinnon, D.S. and B. Freedman.1993. |
| successful hatching of chicken eggs,33 and | | | | Effects of silvicultural use of the herbicide |
| caused feminization or sterility in pheasant | | | | glyphosate on breeding birds of regenerating |
| chicks.31 Herbicides can also adversely | | | | clearcuts in Nova Scotia, Canada. J. Appl. |
| effect birds by destroying their habitat. | | | | Ecol. 30(3):395-406. |
| Glyphosate treatment in clear cuts caused | | | | |
| dramatic decreases in the populations of | | | | 32. Marx, J et al. 1999. The relationship |
| birds that had lived there.32 | | | | between soil and water, how soil amendments |
| | | | and compost can aid in salmon recovery. Soils |
| Beneficial Soil Microorganisms One spoonful | | | | for Salmon 1-18. 33. Savonen, C. 1997. Soil |
| of healthy soil has millions of tiny | | | | microorganisms object of new OSU service. |
| organisms including fungi, bacteria, and a | | | | Good Fruit Grower. 1995/6other.html. |
| host of others. These microorganisms play a | | | | |
| key role in helping plants utilize soil | | | | 34. Pell, M., B. Stenberg, and L. |
| nutrients needed to grow and thrive. | | | | Torstensson. 1998. Potential denitrification |
| Microorganisms also help soil store water and | | | | and nitrification tests for evaluation of |
| nutrients, regulate water flow, and filter | | | | pesticide effects in soil. Ambio 27:24-28. |
| pollutants.34 The heavy treatment of soil | | | | |
| with pesticides can cause populations of | | | | 35. Santos, A. and M. Flores. 1995. Effects |
| beneficial soil microorganisms to decline. | | | | of glyphosate on nitrogen fixation of |
| According to soil scientist Dr. Elaine | | | | free-living heterotrophic bacteria. Lett. |
| Ingham, "If we lose both bacteria and fungi, | | | | Appl. Microbiol. 20:349-352. |
| then the soil degrades. Overuse of chemical | | | | |
| fertilizers and pesticides have effects on | | | | 36. Moorman, T.B. et al. 1992. Production of |
| the soil organisms that are similar to human | | | | hydrobenzoic acids by Bradyrhizobium |
| overuse of antibiotics. Indiscriminate use of | | | | japonicum strains after treatment with |
| chemicals might work for a few years, but | | | | glyphosate. J. Agric. Food Chem. 40:289-293. |
| after awhile, there aren't enough beneficial | | | | |
| soil organisms to hold onto the nutrients."35 | | | | 37. Fabra, A., R. Duffard, and A. Evangelista |
| For example, plants depend on a variety of | | | | de Duffard. 1997. Toxicity of |
| soil microorganisms to transform atmospheric | | | | 2,4-dichlorophenoxyacetic acid in pure |
| nitrogen into nitrates that plants can use. | | | | culture. Bull. Environ. Contam. Toxicol. |
| Common landscape herbicides disrupt this | | | | 59:645-652. |
| process: triclopyr inhibits soil bacteria | | | | |
| that transform ammonia into nitrite36; | | | | 38. Arias, R.N. and A. Fabra de Peretti. |
| glyphosate reduces the growth and activity of | | | | 1993. Effects of 2,4- dichlorophenoxyacetic |
| both free-living nitrogen-fixing bacteria in | | | | acid on Rhizobium sp. growth and |
| soil37 and those that live in nodules on | | | | characterization of its transport. Toxicol. |
| plant roots38; and 2,4-D reduces nitrogen | | | | Lett. 68:267-273. |
| fixation by the bacteria that live on the | | | | |
| roots of bean plants,39,40 reduces the growth | | | | 39. Singh, J.B. and S. Singh. 1989. Effect of |
| and activity of nitrogen-fixing blue-green | | | | 2,4-dichlorophenoxyacetic acid and maleic |
| algae, 41,42 and inhibits the transformation | | | | hydrazide on growth of bluegreen algae |
| by soil bacteria of ammonia into | | | | (cyanobacteria) Anabaena doliolum and |
| nitrates.43,44 Mycorrhizal fungi grow with | | | | Anacystis nidulans. Sci. Cult. 55:459-460. |
| the roots of many plants and aid in nutrient | | | | |
| uptake. These fungi can also be damaged by | | | | 40. Tözüm-Çalgan, S.R.D. and S. |
| herbicides in the soil. One study found that | | | | Sivaci-Güner. 1993. Effects of 2,4-D and |
| oryzalin and trifluralin both inhibited the | | | | methylparathion on growth and nitrogen |
| growth of certain species of mycorrhizal | | | | fixation in cyanobacterium, Gloeocapsa. |
| fungi.45 Roundup has been shown to be toxic | | | | Intern. J. Environ. Stud. 23:307-311. |
| to mycorrhizal fungi in laboratory studies, | | | | |
| and some damaging effects were seen at | | | | 41. Martens, D.A. and J.M. Bremner. 1993. |
| concentrations lower than those found in soil | | | | Influence of herbicides on transformations of |
| following typical applications. 46,47 | | | | urea nitrogen in soil. J. Environ. Sci. |
| Triclopyr was also found to be toxic to | | | | Health B 28:377-395. |
| several species of mycorrhizal fungi,48 and | | | | |
| oxadiazon reduced the number of mycorrhizal | | | | 42. Frankenberger, W.T., Jr. and M.A. |
| fungal spores.49 | | | | Tabatabai. 1991. Factors affecting |
| | | | L-asparaginase activity in soils. Biol. Fert. |
| Conclusion Pesticides have contaminated | | | | Soils 11:1- 5. |
| almost every part of our environment. | | | | |
| Pesticide residues are found in soil and air, | | | | 43. Bakalivanov, D. and O. Kostov. 1981. Soil |
| and in surface and ground water across the | | | | microbiological assessment of toxicity of |
| nation, and urban pesticide uses contribute | | | | alkanoate, amide and other herbicides. Acta |
| to the problem. Pesticide contamination poses | | | | Microbiol. Acad. Sci. Hung. 28:141-146. |
| significant risks to the environment and | | | | |
| non-target organisms ranging from beneficial | | | | 44. Beyrle, H.F. et al. 1995. Colonization of |
| soil microorganisms, to insects, plants, | | | | Orchis morio protocorms by a mycorrhizal |
| fish, and birds. Contrary to common | | | | fungus: effects of nitrogen nutrition and |
| misconceptions, even herbicides can cause | | | | glyphosate in modifying the responses. Can. |
| harm to the environment. In fact, weed | | | | J. Bot. 73:1128-1140. |
| killers can be especially problematic because | | | | |
| they are used in relatively large volumes. | | | | 44. Jofré, E. et al. 1996. |
| The best way to reduce pesticide | | | | 2,4-Dichlorophenoxyacetic acid affects the |
| contamination (and the harm it causes) in our | | | | attachment of Azospirillum brasilense Cd to |
| environment is for all of us to do our part | | | | maize roots. Toxicol. 107:9-15. |
| to use safer, non-chemical pest control | | | | |
| (including weed control) methods. | | | | 45. Kelley, W.D. and D.B. South. 1978. In |
| | | | vitro effects of selected herbicides on |
| References: | | | | growth and mycorrhizal fungi. Weed Science |
| | | | Society of America Meeting . Auburn |
| 1. Cooperative Extension Service Pesticide | | | | University, Auburn, Alabama. Pg. 38. |
| Information Project.1993. Extoxnet: | | | | |
| Chlorpyrifos. Corvallis, Oregon: Oregon State | | | | 46. Estok, D., B. Freedman, and D. Boyle. |
| University (September). | | | | 1989. Effects of the herbicides 2,4-D, |
| | | | glyphosate, hexazinone, and triclopyr on the |
| 2. US EPA. 2000. Reregistration eligibility | | | | growth of three species of ectomycorrhizal |
| science chapter forchlorpyrifos. Fate and | | | | fungi. Bull.Environ. Contam. Toxicol. |
| environmental risk assessment chapter(Revised | | | | 42:835-839. |
| June). chlorpyrifos/efedrra1.pdf. | | | | |
| | | | 47. Chakravarty, P. and S.S. Sidhu. 1987. |
| 3. Cox, C. 2000. Lethal lawns: diazinon use | | | | Effects of glyphosate, hexazinone and |
| threatens salmonsurvival. Journal of | | | | triclopyr on in vitro growth of five species |
| Pesticide Reform 20(2). 2-7.72. U.S. EPA. | | | | of ectomycorrhizal fungi. European Journal of |
| Office of Prevention, Pesticides, and Toxic | | | | Forest Pathology 17:204-210. |
| Substances. 1996. Reregistration eligibility | | | | |
| decision (RED):trifluralin. Washington, D.C., | | | | 48. Moorman, T.B. 1989. A review of pesticide |
| April. | | | | effects on microorganisms and microbial |
| | | | processes related to soil fertility. Journal |
| 4. Koyama, J. 1996. Vertebral deformity | | | | Prod. Agric. 2(1): 14-23. |